docs: def halt(self, subid, params=None):
          ''' /v1/server/halt
          POST - account
          Halt a virtual machine. This is a hard power off (basically, unplugging
          the machine). The data on the machine will not be modified, and you
          will still be billed for the machine. To completely delete a
          machine, see v1/server/destroy
  
          Link: https://www.vultr.com/api/#server_halt
          '''
          params = update_params(params, {'SUBID': subid})
          return self.request('/v1/server/halt', params, 'POST')